Exhaust treatment system and method of assembly

ABSTRACT

An exhaust treatment system for an internal combustion engine comprises an insulating and cushioning mat material disposed in the exhaust treatment system and a film laminate sleeve vacuum packed and sealing the insulating and cushioning mat material therein.

CROSS-REFERENCES TO RELATED APPLICATIONS

This patent application claims priority to U.S. Provisional Patent Application Ser. No. 61/379,538 filed Sep. 2, 2010, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

Exemplary embodiments of the present invention relate to exhaust systems for internal combustion engines and, more particularly, to an exhaust treatment system and method of assembly.

BACKGROUND

A typical exhaust system for an internal combustion engine may involve the placement of an exhaust treatment system or assembly (typically an oxidation catalyst device) in close proximity to the exhaust manifold of the internal combustion engine. This exhaust treatment system, in this example referred to as a close-coupled exhaust treatment system, is typically a catalytic device in which regulated exhaust constituents (ex. CO, HC, NO_(x), Particulates, etc.) may be converted to non-regulated compounds (ex. CO₂, H₂O, etc.). The close coupling to the engine exhaust manifold minimizes thermal loss from the exhaust gas, as it travels between the engine and the exhaust treatment system, resulting in higher temperatures and quicker catalytic activation. Minimizing thermal loss is important since the catalyst compounds that are typically used for treating engine exhaust gas operate at optimal efficiency at temperatures in excess of 350° C.

In an exemplary embodiment of the exhaust treatment system discussed, the catalytic device may be disposed in a housing or canister that comprises a single piece cylindrical or near cylindrical member that is closed at each end by an inlet or an outlet cone that is in fluid communication with the exhaust system of the internal combustion engine. The catalytic device is typically constructed as a catalyst coated, flow-though substrate constructed of ceramic or metal that is supported within the canister by an insulating and cushioning mat material that is interposed between the perimeter of the flow-through substrate and an inner wall of the canister.

Assembly of the exhaust treatment system may involve the use of a stuffing ram in which the catalyst coated, flow-through substrate is wrapped in the mat material and then axially inserted (i.e. “stuffed”) by the stuffing ram through a stuffing shoe and into the canister. The stuffing shoe compresses the mat material as it enters the canister allowing it to re-expand once the substrate is positioned properly in the canister. While the process can be effective for the assembly of the exhaust treatment system, the stuffing shoe may, at times, misalign or damage the mat causing durability issues during operation of the internal combustion engine.

SUMMARY OF THE INVENTION

In an exemplary embodiment of the present invention, a method of assembling an exhaust treatment system for an internal combustion engine comprises a substrate disposed in a canister and an insulating and cushioning mat material interposed between an outer surface perimeter of the substrate and an inner wall of the canister comprising, inserting the insulating and cushioning mat material into a film laminate sleeve, subjecting the insulating and cushioning mat material to a compression process that compresses the mat material to a nominal thickness that is less that that of an uncompressed thickness, sealing the insulating and cushioning mat material in the film laminate sleeve and inserting the mat into the canister.

In another exemplary embodiment of the present invention, an exhaust system for an internal combustion engine comprises an exhaust treatment system having a substrate disposed in a canister, an insulating and cushioning mat material interposed between an outer surface perimeter of the substrate and an inner wall of the canister and a film laminate sleeve compressing and sealing the insulating and cushioning mat material to a nominal thickness that is less than that of an uncompressed thickness.

In yet another exemplary embodiment of the present invention, an exhaust treatment system for an internal combustion engine comprises an insulating and cushioning mat material disposed in the exhaust gas treatment system and a film laminate sleeve vacuum packed and sealing the insulating and cushioning mat material to a nominal thickness that is less than that of an uncompressed thickness.

The above features and advantages, and other features and advantages of the present invention are readily apparent from the following detailed description of the invention when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features, advantages and details appear, by way of example only, in the following detailed description of the embodiments, the detailed description referring to the drawings in which:

FIG. 1 is a front view of an internal combustion engine and associated exhaust gas treatment system embodying features of the invention;

FIG. 2 is a sectional view of the exhaust treatment system of FIG. 1, embodying features of the invention;

FIG. 3 is an illustration of the insulating and cushioning mat material of the exhaust treatment system of FIG. 2 in an uncompressed state;

FIG. 4 is an illustration of the insulating and cushioning mat material of the exhaust treatment system of FIG. 2 in a compressed state, prior to installation therein; and

FIG. 5 is an illustration of an insulating and cushioning mat material and substrate assembly embodying features of the present invention.

DESCRIPTION OF THE EMBODIMENTS

The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

Referring now to FIG. 1, an exemplary embodiment is directed to an exhaust system 10, for the reduction of regulated exhaust gas constituents of an internal combustion engine 12. It is appreciated that the internal combustion engine 12 may be one of various configurations and types, such as gas or diesel, in-line or V-configured. For ease of description and discussion, the disclosure will be discussed in the context of the in-line four cylinder gasoline engine shown. The internal combustion engine 12 includes a cylinder block 14 that is typically constructed of cast iron or a lighter weight alloy such as aluminum. The lower end of the cylinder block 14 is closed by an oil pan 16 while the upper end is closed by a cylinder head 18 and valve cover 20.

In an exemplary embodiment, the cylinder head 18 is associated with an exhaust manifold 26 that is configured to conduct combustion constituents or exhaust gas 28 therefrom. Referring to FIGS. 1 and 2, in an exemplary embodiment, an exhaust treatment system 40 includes a canister 41 that is configured to support a catalyst substrate. In the exemplary embodiment illustrated in the Figures, the exhaust treatment system 40 is configured as a Split Volume Common Can (“SVCC”) Catalytic Converter having a first and a second catalyst substrate 44 and 45, respectively. The catalyst substrates 44, 45 may be constructed of a ceramic honeycomb, a metal honeycomb or other suitable structure.

In an exemplary embodiment, exhaust gas passages 46, that are essentially straight paths from the upstream fluid inlets 48 to the downstream fluid outlets 50 of each substrate 44, 45 are defined by substantially longitudinally extending walls 52 on which various catalytic materials (not shown) are coated so that the exhaust gas 28 that passes through the catalyst substrates 44 and 45 contacts the catalytic material to thereby initiate a chemical conversion process. For example, in an exemplary embodiment, as the exhaust gas 28 traverses the length of the first catalyst substrate 44 a precious metal or Platinum group metal catalyst compound, including platinum group metals such as platinum (Pt), palladium (Pd), rhodium (Rh) or other suitable oxidizing catalysts, or combination thereof, catalyzes the oxidation of carbon monoxide (“CO”) to carbon dioxide (“CO₂”) in the presence of oxygen (“O₂”), as well as catalyzing the oxidation of various hydrocarbons, including gaseous HC and liquid HC particles including unburned fuel or oil as well as HC reductants that may have been introduced into the exhaust gas stream 28 to form H₂O. As the exhaust gas 28 traverses the length of the second catalyst substrate 45 a precious metal or Platinum group metal catalyst compound, including platinum group metals such as platinum (Pt), palladium (Pd), rhodium (Rh) or other suitable oxidizing catalysts, or combination thereof, catalyzes the oxidation of any remaining (i.e. “slipped”) carbon monoxide (“CO”) to carbon dioxide (“CO₂”) in the presence of oxygen (“O₂”), as well as catalyzing the oxidation of various remaining hydrocarbons, including gaseous HC and liquid HC particles including unburned fuel or oil as well as HC reductants that may have been introduced into the exhaust gas stream 28 to form H₂O. Other combinations of catalyst compounds, such as a Selective Catalyst Reduction (“SCR”) catalyst, are of course contemplated and will be selected based on various parameters such as the type of engine (ex. diesel or gasoline) as well as the application of the internal combustion engine 12 and/or the vehicle type in which the engine is operated. It is, of course, contemplated that a single catalyst substrate may be installed in the canister 41 of the exhaust treatment system 40 in place of the first and second catalyst substrates 44 and 45 described above without affecting the scope or application of the invention. Additionally, the substrate or substrates may include un-catalyzed filtration substrates as are commonly used in exhaust particulate traps also without affecting the scope or application of the invention.

Closing a first inlet end 54 of the canister 41 is an inlet end cone 56 that is in fluid communication with the exhaust manifold 26 of the cylinder head 18. The inlet cone 56 is configured to receive exhaust gas 28 for passage through the first and second catalyst substrates 44 and 45, respectively. Similarly, closing the second, outlet end 58 of the canister 41 is an outlet end cone 60 that may be configured in a cone or semi-conical configuration to provide a smooth transition of the exhaust gas 28 to an exhaust gas conduit 62 with which the outlet end cone 60 is in fluid communication.

Referring to particularly to FIGS. 2, 3 and 4, an insulating and cushioning mat material 64 is interposed between the outer surface 66 perimeter of the flow-through substrates 44, 45 and the inner wall 68 of the canister 41. The mat material 64 may be of the type commonly referred to as an intumescent mat or, may be a non-intumescent mat. The selection of the mat material 64 is dependent on the internal combustion engine 12 to which the exhaust treatment system 40 is applied as well as other considerations. Regardless of the type of insulating and cushioning mat material 64 selected, the mat material operates to support the first and second catalyst substrates 44, 45 in the canister 41 against damage from external shock and movement of the substrates therein. In addition, the mat material 64 defines a thermal barrier between the catalyst substrates 44, 45 and the inner wall 68 of the canister 41 the thereby reduce the temperature of the outer wall 70 of the canister 41.

In an exemplary embodiment, and referring particularly to FIGS. 3 and 4, prior to insertion of the first and second catalyst substrates 44, 45 into the canister 41, each substrate is wrapped in a layer of insulating and cushioning mat material 64. The insulating and cushioning mat material 64 is cut or otherwise formed to the external dimensions of the substrates 44, 45. Following sizing, the insulating and cushioning mat material 64 is inserted into a film laminate sleeve 72 and is subjected to compression of the mat material to a nominal thickness “t”, FIG. 4 that is less that that of its uncompressed thickness “T”, FIG. 3. The insulating and cushioning mat material 64 is sealed in the film laminate sleeve 72 in order to maintain the mat in its compressed state. In an exemplary embodiment the compression of the mat material is through application of a vacuum to the film laminate sleeve 72 with subsequent sealing of the sleeve while under vacuum. An alternative to vacuum compression of the mat material is mechanical compression utilizing a suitable press. In an exemplary embodiment, the film laminate sleeve 72 comprises a Low Organic Film Laminate (“LOFL”) that is subject to vaporization, combustion or other form of dissipation when heated to the temperatures experienced by the exhaust treatment system 40. While not limited to an LOFL, the selected film laminate sleeve 72 is selected from a group of laminates that will substantially completely vaporize, combust or otherwise dissipate during heating/operation of the exhaust system 10 to thereby allow the insulating and cushioning mat material 64 to expand to a dimension that provides full support and thermal insulation of the substrates 44, 45 within the canister 41.

In an exemplary embodiment, following the vacuum process that compresses the insulating and cushioning mat material 64 to a nominal thickness “t”, the compressed mat material 64 is wrapped around the substrate or substrates 44, 45 and the mat and substrate assembly is axially inserted into the canister 41. Insertion of the mat and substrate assembly may be through the use of a stuffing ram, as is commonly known. However, in the case of the mat and substrate assembly utilizing the invention disclosed, the insulating and cushioning mat material 64 will require little or no compression by a stuffing shoe, resulting in a low risk of damage thereto.

Upon operation of the internal combustion engine, the LOFL film laminate sleeve 72 will vaporize, combust or otherwise dissolve in the hot exhaust gas environment and the insulating and cushioning mat material 64 will expand to fill the gap between the outer surfaces 66 of the substrates 44, 45 and the inner wall 68 of the canister 41. Expansion of the cushioning mat material 64 supports the catalyst substrates 44, 45 in the canister 41 against damage from external shock and movement of the substrates therein and defines a thermal barrier between the catalyst substrates 44, 45 and the inner wall 68 of the canister 40, reducing the temperature of the outer wall 70 of the canister 41.

Referring now to FIG. 5, it is also contemplated that the insulating and cushioning mat material 64 may be wrapped around the catalyst substrates 44, 45 in an uncompressed state such as is illustrated in FIG. 3. Following the application of the insulating and cushioning mat material 64 to the catalyst substrates 44, 45 the mat and substrate assembly 74 may be placed in a film laminate sleeve 72 and vacuum packed to compress the insulating and cushioning mat material 64 about the outer surface 66 of the substrate. The mat and substrate assembly 74 is sealed in the film laminate sleeve 72 at seams 76, for instance, in order to maintain the insulating and cushioning mat material 64 in its compressed state until the mat and substrate assembly 74 is installed into the canister 41 of the exhaust treatment system 40.

While the invention has been described with respect to the application of an insulating and cushioning mat material disposed between the catalyst substrate and the canister of an exhaust treatment system, it is contemplated that, as such, the invention will apply equally to any areas of an exhaust treatment system that require the disposition of such a mat.

While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the present application. 

What is claimed is:
 1. A method of assembling an exhaust treatment system for an internal combustion engine comprising a substrate disposed in a canister and an insulating and cushioning mat material interposed between an outer surface perimeter of the substrate and an inner wall of the canister comprising: inserting the insulating and cushioning mat material into a film laminate sleeve; subjecting the insulating and cushioning mat material to a compression process that compresses the mat material to a nominal thickness that is less that that of an uncompressed thickness; sealing the insulating and cushioning mat material in the film laminate sleeve; and inserting the mat into the canister.
 2. The method for assembly of an exhaust treatment system of claim 1, further comprising: operating the internal combustion engine to vaporize, combust or otherwise dissolve the film laminate sleeve in a hot exhaust gas environment to expand the insulating and cushioning mat material.
 3. The method for assembly of an exhaust treatment system of claim 1, wherein the compression process comprises applying a vacuum to the insulating and cushioning mat material containing film laminate sleeve.
 4. The method for assembly of an exhaust treatment system of claim 1, further comprising: wrapping the compressed insulating and cushioning material around the substrate prior to inserting the mat into the canister; and inserting the mat wrapped substrate into the canister.
 5. The method for assembly of an exhaust treatment system of claim 1, further comprising: wrapping the uncompressed insulating and cushioning material around the substrate; subjecting the mat wrapped substrate to a compression process that compresses the mat material to a nominal thickness that is less that that of an uncompressed thickness; sealing the mat wrapped substrate in the film laminate sleeve; and inserting the mat wrapped and laminate sealed substrate into the canister.
 6. An exhaust system for an internal combustion engine comprising: an exhaust treatment system having a substrate disposed in a canister; an insulating and cushioning mat material interposed between an outer surface perimeter of the substrate and an inner wall of the canister; and a film laminate sleeve compressing and sealing the insulating and cushioning mat material to a nominal thickness that is less than that of an uncompressed thickness.
 7. The exhaust system for the internal combustion engine of claim 6, wherein the compressing and sealing the insulating and cushioning mat material comprises applying a vacuum to the film laminate sleeve.
 8. The exhaust system for the internal combustion engine of claim 6, wherein the film laminate sleeve comprises a film laminate that vaporizes and/or combusts when heated.
 9. The exhaust system for the internal combustion engine of claim 6, wherein the film laminate sleeve comprises a Low Organic Film Laminate.
 10. The exhaust system for the internal combustion engine of claim 6, wherein the substrate comprises a catalyst coated substrate.
 11. The exhaust system for the internal combustion engine of claim 6, wherein the catalyst comprises a precious metal or Platinum group metal catalyst compound, including platinum group metals such as platinum (Pt), palladium (Pd), rhodium (Rh) or other suitable oxidizing catalysts, or combination thereof.
 12. The exhaust system for the internal combustion engine of claim 6, wherein the canister further comprises: a first, inlet end closed by an inlet end cone that is in fluid communication with an exhaust manifold of a cylinder head of the internal combustion engine; and a second, outlet end closed by an outlet end cone that is in fluid communication with an exhaust gas conduit of the exhaust system.
 13. An exhaust treatment system for an internal combustion engine comprising: an insulating and cushioning mat material disposed in the exhaust gas treatment system; and a film laminate sleeve vacuum packed and sealing the insulating and cushioning mat material to a nominal thickness that is less than that of an uncompressed thickness.
 14. The exhaust treatment system for the internal combustion engine of claim 13, wherein the film laminate sleeve comprises a film laminate that vaporizes and/or combusts when heated.
 15. The exhaust treatment system for the internal combustion engine of claim 13, wherein the film laminate sleeve comprises a Low Organic Film Laminate.
 16. The exhaust treatment system for the internal combustion engine of claim 13, wherein the film laminate sleeve is vacuum packed and seals the insulating and cushioning mat material and a catalyst substrate therein.
 17. The exhaust treatment system for the internal combustion engine of claim 16, wherein the substrate comprises a catalyst coated substrate.
 18. The exhaust treatment system for the internal combustion engine of claim 17, wherein the catalyst comprises a precious metal or Platinum group metal catalyst compound, including platinum group metals such as platinum (Pt), palladium (Pd), rhodium (Rh) or other suitable oxidizing catalysts, or combination thereof.
 19. The exhaust treatment system for the internal combustion engine of claim 16, further comprising: a canister housing the film laminate sleeve, the insulating and cushioning mat material and the catalyst substrate therein; a first canister inlet end closed by an inlet end cone that is in fluid communication with an exhaust manifold of a cylinder head of the internal combustion engine; and a second, outlet end closed by an outlet end cone that is in fluid communication with an exhaust gas conduit of an exhaust system. 